Certain washers use a solution, known as a use solution or a working solution, consisting mainly of concentrate, e.g., detergent, and a diluent, e.g., water. As the use solution is utilized and the effects of the detergent concentrate are gradually diminished, the use solution becomes less concentrated and the use solution becomes less effective. At an appropriate time, either the use solution must be changed or additional concentrate must be added to increase the concentration of the concentrate, e.g., detergent, in the use solution to bring the concentration of concentrate in the use solution to within an acceptable range. A user of such a use solution must keep track of the concentration of the use so as to know when to add concentrate to the use solution and how much concentrate to add to the use solution.
Concentration monitors are typically used for this purpose. Concentration monitors determine the amount, for example, on a percentage basis, of concentrate contained in a known use solution. Electrical characteristics of some use solutions vary as a function of the concentration. For example, if a concentrate is more electrically conductive than a diluent, then the conductivity of the use solution will increase as the percentage amount of concentrate is increased in the use solution. Thus, a concentration monitor that could sense the conductivity of the use solution could determine that concentrate needed to be added to the use solution when the conductivity of the use solution dropped to a pre-determined level. A concentration monitor of this type could either, for example, automatically add concentrate to the use solution or, alternatively, could report the concentration level, or sound an alarm, and let the user determine the appropriate course of action to be taken.
Conductivity type concentration monitors typically use a particular cell, a probe for insertion into the use solution, for a particular product concentrate, or class of product concentrate, being monitored. Different use solutions, particularly different types of use solutions for different product classes, e.g., different types of detergents such phosphate and non-phosphate detergents, have different cell constants. A cell constant is the surface area of the conductive agent in the use solution which is exposed to the cell, or probe, monitoring the concentration. A particular cell, or probe, is selected for a use solution containing a particular product, or product class, depending on the cell constant of the use solution.
Newer generations of detergent products, e.g., extruded detergents, have naturally low conductivity. Thus, the cell constant is markedly different for these types of newer detergents as compared with traditional detergents.
Therefore, existing concentration monitors with existing cells, probes, which were designed for traditional detergents, won't work properly with the newer generations of detergents. This requires swapping out a multiplicity of probes in a multiplicity of existing installations with new probes compatible with newer generations of detergent. With a large number of existing installations, swapping out existing probes for new probes would be very costly and time consuming as well as disruptive to existing installations.
In addition, the same probe would not work for both classes of detergent product. This would require the customer (user) to have multiple probes in stock and to actually change probes when a different detergent product, or class of detergent products, is used. The customer would have to insert a different probe whenever a detergent product was changed or a class of detergent products was changed in order to use the proper cell, probe, for the current detergent product, or class of detergent products, being used.